The Short Message Service (SMS) is one of the operator's key services frequently used by the customer.
Traditionally SMS is based on signalling system No. 7 (SS7) architecture as defined by 3rd Generation Partnership Project. The architecture currently standardized by 3GPP allows short message (SM) interworking with internet protocol (IP) based networks, for example using Session Initiation Protocol (SIP) signalling. SIP is an application-layer control protocol for creating, modifying, and terminating dialogs with one or more participants. These dialogs may include Internet multimedia conferences, Internet telephone calls, and multimedia distribution. Members in a dialog can communicate via multicast or via a mesh of unicast relations, or a combination of these. SIP is used as signalling protocol in an internet protocol (IP) multimedia subsystem (IMS).
The 3GPP also standardizes a new charging framework for both IP and legacy SM signalling that includes the definition of a Diameter (i.e. an IP protocol) based online charging interface (Ro) between the Online Charging Server (OCS) and an SMS Router or IP-SM-Gateway. The approach for offline charging based on Rf interface is currently not standardized. The SMS Router can be for example a SM Service Centre (SMSC) or a separate node as architectural options.
Currently a SM can only be sent to one destination. If the sender wants to send the same message to more than one destination (e.g. recipients) then the same SM must be resent. Such retransmission can be launched by the subscriber itself (re-sending of stored sent message) or by a terminal application. In the latter case the sender assigns multiple destinations to the SM he wants to broadcast whereas the terminal application accomplishes it by actually emitting one SM per recipient. This leads to multiple SMS traffic in terms of SMS data, signalling and also for charging.
The operator must consider such intentionally broadcast messages as single events. Hence the core network as well as the charging infrastructure, i.e. the OCS for prepaid subscribers, can face performance issues.